Field of the Invention
The invention relates to a method and a measuring system for the measurement and testing of a mobile-telephone device (UE).
Discussion of the Background
Following after GSM, GPRS and UMTS, HSDPA (High Speed Downlink Packet Access) and UMTS LTE (Long Term Evolution) have risen to prominence as the latest developments in the field of mobile telephone communications. The goal of HSDPA and UMTS LTE is the optimization of the UMTS system with regard to the support of data services. UMTS already offers rapid data services, such as the transmission of high-quality video data at a rate of 384 kbit/s.
Building on this, HSDPA and UMTS LTE utilize new technologies, which allow data rates up to 14 Mbit/s and further increase the capacity of the mobile-communications network as such. As a result, mobile-telephone operators can offer their customers improved multimedia services.
FIG. 1 shows a schematic display of the HDSPA technology, in particular of the logical (and physical) channels used in HDSPA. The introduction of a new transmission channel for user data, the so-called High-Speed (Physical) Downlink Shared Channel, HS-(P)DSCH, is significant. Different users share the resources of the air interface, which are available on this channel. An intelligent algorithm in Node B decides which subscribers receive a data packet at which time.
This decision is communicated to the subscribers via a parallel signal channel, the so-called High-Speed Shared Control Channel, HS-SCCH. By contrast with UMTS, where a new data packet can be transmitted at most every 10 ms, in the case of HSDPA, a packet transmission can take place every 2 ms.
User reply messages regarding channel quality and also packet acknowledgements or negative acknowledgements are provided in the uplink on the so-called High-Speed Dedicated Physical Control Channel, HS-DPCCH. The HS-DPCCH is a physical uplink channel, which is used for the communication of management or control information: HARQ ACK/NACK and Channel-Quality Information. FIG. 2 shows a schematic display of the structure of the HS-DPCCH.
The Channel-Quality Information consists of the so-called CQI value, which relates to the CQI tables, which are described in the 3GPP specification TS 25.214 (“Physical layer procedures”). Different tables for different categories of user equipment (UE) exist, dependent upon the complexity of implementation of the UE. For example, Table 1 shows the CQI table for the UE categories 1 to 6.
TABLE 1CQI mapping Table for UE categories 1 to 6.TransportNumberReferenceCQIBlockof HS-powervalueSizePDSCHModulationadjustmentNIRXRV0N/AOut of range11371QPSK09600021731QPSK032331QPSK043171QPSK053771QPSK064611QPSK076502QPSK087922QPSK099312QPSK01012623QPSK01114833QPSK01217423QPSK01322794QPSK01425834QPSK01533195QPSK0163565516-QAM0174189516-QAM0184664516-QAM0195287516-QAM0205887516-QAM0216554516-QAM0227168516-QAM0237168516-QAM−1247168516-QAM−2257168516-QAM−3267168516-QAM−4277168516-QAM−5287168516-QAM−6297168516-QAM−7307168516-QAM−8
The CQI values regularly reported by the user equipment UE are evaluated through Node B as a suggestion regarding how the HS-(P)DSCH is to be formatted. With this format, the user equipment (UE) anticipates the resulting block-error rate of the HS-DSCH as disposed below 0.1. The higher the CQI value, the higher the specification of the transmission format of the HS-DSCH will be, that is to say, the better the quality of the radio connection must be.
For example, if the user equipment (UE) reports a CQI value of 14 according to Table 1, it suggests an HS-(P)DSCH format with transmission-block size 2583 bits, 4 channels and QPSK (quadrature phase shift keying) modulation. If an HS-(P)DSCH is formatted in this manner, the transmission-block error rate of the HS-DSCH is estimated as disposed below 0.1. If Node B ignores the suggestion of the user equipment (UE) and selects a transmission format with higher specifications according to a higher CQI value, a higher transmission-block error rate would very probably occur on the HS-DSCH. Accordingly, Node B should ideally select a transmission format according to the recommendation from the user equipment (UE).
The selection of channel coding and modulation methods dependent upon the transmission quality is also summarised under the title “Adaptive Modulation and Coding Method” (AMC).
In order to secure a robust data transmission, HSDPA also uses a so-called HARQ (Hybrid Automatic Repeat Request) protocol. If a user device (UE) receives an error data packet, it requests the data packet again. Upon repetition of the packet transmission, Node B can select another type of coding, which allows the subscriber an improved reception (incremental redundancy). This type of coding is referred to in the specialist terminology as “redundancy and constellation version”, or abbreviated as “redundancy version” (RV version) or redundancy type. If a packet has been transferred to the user equipment (UE), Node B must wait until the acknowledgement (ACK) or negative acknowledgement (NACK) for this packet has been received (so-called “stop-and-wait” transmission mechanism). In the intervening time, Node B can transmit further data packets to this user equipment (UE) via other HARQ processes. A user device must support up to 8 parallel HARQ processes, which are equivalent to up to 8 independent HARQ “stop-and-wait” transmission mechanisms.
Furthermore, methods for the exploitation of several antennas per transmitter and/or receiver (Multiple Input Multiple Output or MIMO), which exploit so-called spatial diversity, wherein (identical) antennas are erected at a given spacing distance from one another but with the same orientation, and/or polarization diversity, according to which two antennas are erected with an angular difference of 90 degrees relative to one another, in order to reduce interference effects in the radio transmission and to increase the peak throughput by means of code reuse, are known and can, in principle, be used within the framework of HSDPA. Reference is made to the technical report “Physical layer aspects of UTRA High-Speed Downlink Packet Access” (3GPP-specification 3GPP TR 25.848 specification) for the details.
The structure of an HSDPA or UMTS LTE compatible network requires special test and measurement solutions. In particular, test and measurement solutions are required, which provide information about a potential error matching of the user equipment used (clipping) or its general defectiveness, about a defective implementation and about the resource efficiency of the equipment used (performance).